Water cooling in a small HTPC

Howdy everybody,
I have a small home theater PC (Moncaso 312b). As you can see in the picture below (From google search, this isn't mine) space is VERY limited. That said I'd love to water cool the thing. As a HTPC I'd prefer it to be much quieter than it is, and it is already running hot as is (no overclocking or anything).

I know very little about watercooling in general, and am wondering if it is even possible in such a space constrained system. At first I thought there was no way, but then this little guy caught my eye: http://www.frozencpu.com/products/1...ini_II_Dual_40mm_Radiator.html?tl=g30c95s1311

The back of the MonCaso supports space for 3 side by side 40mm fans so this radiator might actually work. That said I have no idea what to do for a reservoir or pump. Any thoughts on the smallest but yet still effective components around? Also I noticed that the radiator I linked above says that it supports hoses with inner dimensions of 8mm. That doesn't seem to give with either 1/2 or 3/8ths hosing... so what's the deal there?

Thanks!

First off, what's your goal? If you want silence in a case like that, I don't think watercooling is necessarily going to get you there. If you want an interesting project, though, then I say go for it.

The back of the MonCaso supports space for 3 side by side 40mm fans so this radiator might actually work.

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That's very little surface area - actually less than a single 80mm radiator. 40mm fans are screamers, too, so if this is your only radiator it's going to perform much worse than your current air cooling. To make this quieter, you'll probably have to find at least 120mm of radiator space, likely more.

In general, with such a tight amount of space, you're going to want a small pump (like the MCP355) and 3/8" ID tubing. Routing is going to be a pain, same deal with maintenance. Usually fairly experienced watercoolers take up projects like this. Not to say you can't or you shouldn't, just that it's going to be a fair amount of work and modding. That gets back to the question about your goals that I asked first.

If you want to quiet the system down, nothing more, then you can probably start undervolting and/or underclocking components to get heat down. That, and the case looks poorly ventilated.

I don't expect silence, but right now to keep it cool enough to run I've had to add additional fans to places where fans aren't supposed to be. Currently the system has a Scythe Shuriken CPU cooler, 2 80mm fans zip-tied into the bottom of the case and 3 40mm fans across the back.

The goal is to reduce some of that noise by eliminating some fans by going the water cooling route. Ventilation in the case is poor and I was hoping that the higher efficiency of water cooling would reduce the number of fans required in the system. If, as you say the radiator I linked is going to be a WORSE solution than a poorly ventilated air cooled system then it's probably a non starter. Is that really the case though? Wouldn't water cooling eliminate the problem of having poor airflow in the case, since airflow isn't what is cooling the system in the first place?

I'm just gonna leave this here for inspiration: http://www.overclockers.com/forums/showthread.php?t=687727

If, as you say the radiator I linked is going to be a WORSE solution than a poorly ventilated air cooled system then it's probably a non starter. Is that really the case though? Wouldn't water cooling eliminate the problem of having poor airflow in the case, since airflow isn't what is cooling the system in the first place?

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Your current CPU cooler has a 100mmx100mm fan on it. That's 100cm^2 of fan area. Three 40mm fans is 48cm^2 of fan area. So you're already making a big compromise there. You can make sure the radiator get cool outside air, which helps the problem somewhat, but that's still a very small amount of surface area with which to cool your processor. You'd need fast, loud 40mm fans, and that kind of defeats the purpose.

Watercooling just pushes heat around efficiently. Instead of dissipating the heat directly from the processor, heat is absorbed in the water and then dissipated in the radiator. The reason it works well is because most of us use a large amount of radiator space, generally 3x 120mm fans or more. That's a big improvement from your standard CPU cooler with a 120mm fan. But the heat still has to go somewhere, and if the radiator gets less airflow and surface area than your heatsink provides, it's not an improvement. That's why I'm saying this is going to be a tricky project - you've got to find room for relatively large radiators either inside or outside your case.

This is an HTPC, so you're not overclocking it? I think it makes more sense to:
a) Identify your biggest sources of noise and find a way to eliminate them
b) Undervolt and possibly underclock your GPU and CPU to lower the amount of heat the system produces

johan851 said:

Watercooling just pushes heat around efficiently. Instead of dissipating the heat directly from the processor, heat is absorbed in the water and then dissipated in the radiator. The reason it works well is because most of us use a large amount of radiator space, generally 3x 120mm fans or more. That's a big improvement from your standard CPU cooler with a 120mm fan.

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Yes but heat transfer for water is significantly higher than heat transfer for air. The thermal conductivity coefficient of water ranges between 5 and 10 times that of air. I understand that these things don't scale well, but the bottom line is that an air cooled surface of 100x100 mm is not as good as a similar water cooled surface of 100x100 mm. It's why we have water in our car radiators instead of just channeling air into the engine.

That said, you folks have the real experience, and what I'm hearing is that while water cooling may be mathematically better, in practice it isn't as much as one would think, and likely not enough to make up the drop from 10,000 square mm to 3200 mm?

Undervolting isn't really a desirable option.

in practice it isn't as much as one would think, and likely not enough to make up the drop from 10,000 square mm to 3200 mm?

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I don't think you're understanding me. Regardless of how efficiently water transfers heat, it's still a heat transfer mechanism. You still need surface area somewhere to dissipate that heat into the air. And if your surface area is too small, the water will continue to heat up until it reaches equilibrium at a temperature much higher than the surrounding air. Then you're not cooling your CPU with room temperature water, you're cooling it with water that's 15-20C warmer than room temperature and you've lost all of the gains you would have had by using water.

It doesn't matter if you're using water to move heat to aluminum fins or using aluminum to move heat to aluminum fins. If you don't have enough surface area, your temps will go up.

It's why we have water in our car radiators instead of just channeling air into the engine.

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The real problem is that there's not enough surface area in the engine for channeling air to be an effective cooling mechanism.

Your right in saying water is a much better medium than air to pull heat awa from the main components. Primarily the CPU and GPU.

What you have to understand the heat is removed from parts by water. But the heat is then dissipated through fins back into the air, like a HUGE heatsink. If the radiator isn't sized properly, the heat stays in the water and your temps could actually be higher, and possibly keep rising till you have thermal shutdow.

You can't fool physics, and watercooling works if you go with the general rules of watercooling. You don't have enough radiator planned. Maybe you could buy better quality fans and stay air cooled that have better pressure ratings at less RPMs, but there is really no PC testing done on 40mm fans. Well unless we go back 15 years.

You could get another case.

You also could have an external radiator mounted on the TV stand etc. Been done, and some very nicely. Use Koolance self sealing quick disconnects when the 6 month drain/refill is done and the annual 100% teardown.

A new case with 80mm or even 120mm fans is cheaper, less hassle, and quieter.

johan851 said:

I don't think you're understanding me. Regardless of how efficiently water transfers heat, it's still a heat transfer mechanism. You still need surface area somewhere to dissipate that heat into the air. And if your surface area is too small, the water will continue to heat up until it reaches equilibrium at a temperature much higher than the surrounding air.

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I get that... but the question is 'how much surface area is enough'? Since water transmits heat better than air, it will require less area to dissipate the same amount of heat as it will do so faster.

For example, let's say Air has a cooling coefficient of 1 and water of 5. Water will dissipate the same amount of heat in 1 cubic CM as air will in 5 cubic CM. I guess what I was trying to get at is that I saw you comparing the area of an air cooler to a water one and I don't think they're linearly comparable.

That said, your message "This isn't enough space" is coming through. I do wonder why such a radiator is even offered. I was under the (perhaps mistaken?) impression that MagiCool was a respected brand.

djc6535 said:

I get that... but the question is 'how much surface area is enough'? Since water transmits heat better than air, it will require less area to dissipate the same amount of heat as it will do so faster.

For example, let's say Air has a cooling coefficient of 1 and water of 5. Water will dissipate the same amount of heat in 1 cubic CM as air will in 5 cubic CM. I guess what I was trying to get at is that I saw you comparing the area of an air cooler to a water one and I don't think they're linearly comparable.

That said, your message "This isn't enough space" is coming through. I do wonder why such a radiator is even offered. I was under the (perhaps mistaken?) impression that MagiCool was a respected brand.

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water can only dissipate heat if it is evaporating, in this case it isnt. The only way it is losing the heat is through the fins of the radiator in convection, which in turn would have to be the same size as a heatsink to dissapate the same ammount of heat, reason why water cooling is better is because you can have a huge rad alot larger (or more surface area) than you can a heatsink and some other stuff effect it too like the efficiency it pulls heat out from the base. due to the water being forced through micro channels of the block vs the vapor in the heatpipes of a cooler doing it naturally and so on an so fourth.

example a 40mm rad sint gonna be as good as a 80mm heatsink.... ever an 80mm heatsink will never be as good as a 120 mm rad ect. a good 120 heatsink can be just as good as a 120mm radiator water system.a good 80cm hsf can be as good as an 80 cm radiator. depends on how its setup.

water can only dissipate heat if it is evaporating, in this case it isnt. The only way it is losing the heat is through the fins of the radiator in convection, which in turn would have to be the same size as a heatsink to dissapate the same ammount of heat, reason why water cooling is better is because you can have a huge rad alot larger (or more surface area) than you can a heatsink and some other stuff effect it too like the efficiency it pulls heat out from the base. due to the water being forced through micro channels of the block vs the vapor in the heatpipes of a cooler doing it naturally and so on an so fourth.

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Exactly. The statement "Since water transmits heat better than air, it will require less area to dissipate the same amount of heat as it will do so faster" is fundamentally incorrect because it matters HOW the water is dissipating heat. In the case of a radiator, the water is dissipating heat into the air. So air performance is still paramount.